Nuclear imaging, such as positron emission tomography (PET), generates scintillation pulses based on receipt of positrons at photo detectors during imaging. The scintillation pulses are resolved in respect to time of origin (or time-of-flight (TOF)) and energy. Current systems use operational amplifiers (op-amps) to interface photomultiplier tube (PMT) anode outputs with data acquisition and processing boards. Very-high bandwidth and low noise buffer amplifiers are needed to convert the PMT anode current outputs to a voltage input of the data acquisition and processing boards. Similarly, a very high bandwidth and low noise summing amplifier is needed to sum multiple PMT pulses into energy signals to provide PET timing information through analog timing pickoff methods.
The use of high-bandwidth low-noise summing and buffer amplifiers results in increased cost and reduced reliability in TOF-PET data acquisition electronics. In addition, summing of the PMT anode outputs creates a bottleneck for the analog timing pick-off circuits. A conventional summing combines multiple PMT anode outputs through a high-speed op-amp, making it difficult to meet the high slope-to-noise ratio (NSR) requirements. Conventional systems further branch broadband signals into two paths for positioning and timing. Such branching is inefficient and under optimizes the signal-to-noise ratio (SNR) for positioning and energy and/or the NSR for timing.